Sorted By Test Name - Mayo Medical Laboratories

CAHBS
84113
Congenital Adrenal Hyperplasia (CAH) Newborn Screening,
Blood Spot
Clinical Information: Congenital adrenal hyperplasia (CAH) is a group of disorders caused by
inherited defects in steroid biosynthesis, in particular, 21-hydroxylase deficiency (approximately 90% of
cases) and 11-beta hydroxylase deficiency (approximately 5% of cases). The overall incidence of the
classic form of 21-hydroxylase deficiency is approximately 1 in 15,000 live births. Individuals with CAH
may present with life-threatening, salt-wasting crises in the newborn period and incorrect gender
assignment of virilized females as a result of reduced glucocorticoids and mineralocorticoids and elevated
17-hydroxyprogesterone (17-OHP) and androgens. Hormone replacement therapy, when initiated early,
enables a significant reduction in morbidity and mortality. Therefore, newborn screening for CAH is
desirable and has been implemented in all 50 states. Immunoassays are typically used to quantify 17-OHP
as a marker for CAH. However, these immunoassays are hampered by cross-reactivity of the antibodies
with other steroids, yielding a high rate of false-positive results. Tandem mass spectrometry allows for the
simultaneous specific determination of 17-OHP and other steroids, such as androstenedione, cortisol,
11-deoxycortisol, and 21-deoxycortisol. Application of this technology to the determination of steroids in
newborn screening blood spots significantly enhances the correct identification of patients with CAH and
reduces the number of false-positive screening results.
Useful For: Second-tier testing of newborns with abnormal screening result for congenital adrenal
hyperplasia
Interpretation: Findings of a 17-hydroxyprogesterone (17-OHP) value >7.0 ng/mL in males or >4.0
ng/mL in females, and a high (17-OHP + androstenedione)/cortisol ratio (controls: < or =2.5) are
supportive of the initial abnormal newborn screening result. Findings of an 11-deoxycortisol value >10.0
ng/mL or 21-deoxycortisol >1.6 ng/mL with elevated 17-OHP further support the abnormal newborn
screening result and increase the diagnostic specificity. Clinical and laboratory follow-up is strongly
recommended.
Reference Values:
17-HYDROXYPROGESTERONE
Males: